The present invention relates to a device ensuring safety and protection of the unit by which at least one continuous cigarette rod is dried and sealed, in cigarette manufacturing machines.
Machines of this type are designed to fashion at least one continuous cigarette rod, starting with a strip of paper uncoiled from a supply reel and a mass of shredded tobacco directed into the machine by suitable feed means.
Thereafter, the continuous rod is cut transversely into discrete lengths which may then undergo other manufacturing operations, for example the addition of a filter tip, before being conveyed ultimately to a wrapping machine.
The continuous rod is fashioned substantially by uncoiling and directing the strip of paper into a suitably profiled guide or channel appearing arched in cross section, of which the radius of curvature varies progressively until assuming a constant and substantially cylindrical shape of radius identical to that of the cigarette in production. Naturally enough, the shredded tobacco is directed into the channel together with the strip of paper.
Just prior to emergence of the final cylindrical shape in which the longitudinal edges of the strip of paper are overlapping and in mutual contact, a layer of gum is inserted between the joined edges by suitable applicators.
Immediately thereafter, the longitudinal edges of the strip are brought together and caused to bond one to the other, thereby moulding the strip into its final cylindrical shape around the filling of tobacco.
Once beyond the gumming station, the rod is cut into discrete lengths and conveyed to successive work stations.
Machines of the type in question are characterized by high operating speeds, hence high feed rates (of the strip first, and of the formed rod thereafter), such that the gum is often not completely dried at the moment when the transverse cut is effected. Clearly, a contingency of this nature can give rise to many drawback, given that an insecurely sealed cigarette rod could break open during the cutting operation, and the relative cutting means would soon become fouled if used to sever a rod in which the gum were not yet completely dried. To avoid such occurrences an intermediate drying and sealing unit is installed between the gumming and cutting stations, consisting essentially in a heat plate capable of movement between a position distanced from the cigarette rod, and a position close to the rod, substantially in contact with the overlapping longitudinal edges of the strip of paper. The movement of the plate toward the position of substantial contact is brought about automatically in most instances, when the cigarette manufacturing machine is set in motion.
This can be hazardous for the machine operator, however, who might encroach on the area in which the heat plate moves and operates precisely at the moment when the plate approaches the cigarette rod, resulting in injuries or burns. Accordingly, the object of the present invention is to overcome the drawback outlined above.